1. Field of the Invention
This invention relates in general to the field of portable communication apparatus and in particular to methods and apparatus adaptable to portable communication devices to provide knowledge to a user as to whether the devices are intrinsically safe for operation in a hazardous environment.
2. Description of the Prior Art
There are many locations, structures, or buildings where a spark from an electrical device could result in an explosion and/or a fire. Usually, such areas are filled with air and a combustible vapor or dust such that the air molecules completely surround the particles of combustible material. The presence of the surrounding air provides an atmosphere which is highly combustible because of the oxidizing effect of the oxygen in the air. An electrical spark in such an environment could, therefore, cause rapid combustion resulting in an explosion.
To lessen the changes of creating an explosion in a vapor or dust-laden atmosphere, intrinsically safe electronic devices have been developed where sparking is substantially or completely eliminated from the connection, operation and disconnection of the electrical devices. Industry standards have been developed so as to define the parameters of an intrinsically safe device throughout the many fields of industry in order to ensure the prevention of an explosion.
Due to rapid advances in technology, many new portable devices in general and portable communication devices in particular are being developed, sold and used. Since portable communication devices necessarily use a battery or batteries for operation, there exists the possibility of a spark being generated when the battery or batteries are removed and replaced. For the most part, the intrinsically safe standards have been applied to portable communication devices and an end user can obtain an intrinsically safe product which can be safely used in a hazardous environment.
In the prior art, some manufacturers label their batteries with a notice stating that the battery is intrinsically safe. On the other hand, other manufacturers might not so label the batteries. Then too, the label on a properly labeled battery may fall off or be taken off so that a user of the communication device can not know or verify whether the battery is intrinsically safe.
In some communication devices having a display screen, an electronic message indicates that the device is intrinsically safe. With these types of devices, an included electronically programmable read only memory chip (EPROM) is preprogrammed to indicate to the user that the device is intrinsically safe or includes an intrinsically safe option. In this manner, a person who is not the original purchaser and does not know that the intrinsically safe option is included with the device may read such information on the display screen of the device.
However, there are occasions in the prior art where an intrinsically safe device has lost this option. For example, the battery which originally came with the device and which is intrinsically safe may have inadvertently been replaced with a battery that does not have this option. A subsequent user would be reading the display screen believing that the device is fully intrinsically safe whereas only the device itself and not the battery is intrinsically safe. Obviously, this could result in a very dangerous situation. While two-way radios are particularly susceptible to being used with a battery which is not intrinsically safe, there exist many other electronic devices, such as cell phones, pagers, wireless accessories, and the like which are potentially dangerous to use in a hazardous environment.
What is needed is a technique which will inform a user whether an electronic device and the battery associated therewith are each intrinsically safe to be used in a hazardous environment.
The present invention accomplishes the above-stated primary objective and overcomes the aforestated prior art problems by providing simple but effective methods and apparatus for determining whether a device and the battery or batteries associated with a battery operated device are each intrinsically safe as may be determined by a fair reading and interpretation of the entire specification herein.